1. Field of the Invention
The present invention relates to an emulsion dispersing device and method which may be suitably employed in an asphalt finisher or other type of paving machine.
This application is based on patent application No. Hei 9-55564 filed in Japan, the content of which is incorporated herein by reference.
2. Description of the Related Art
When applying an asphalt mixture on top of a cement or bitumen material, an emulsion such as asphalt is typically dispersed on top of the base, in order to ensure good adhesion of the asphalt mixture thereto.
In conventional emulsion dispersing devices developed for this purpose, a dispersing nozzle which is opened and closed by an opening/closing means; an emulsion tank for storing the emulsion; an emulsion pump for sending the emulsion in the emulsion tank to the dispersing nozzle and spraying the emulsion from the nozzle in a roughly elliptical pattern; and a control device for controlling the emulsion pump; are provided to a vehicle such as an asphalt finisher. The control device control the rotating speed of the emulsion pump during dispersion of the emulsion, so that the rate of emulsion dispersion reaches a set value.
For reference, an example of the typical capacity of a conventional emulsion dispersing device follows below.
emulsion dispersing rate: 0.2.about.1.0 liters/m.sup.2 PA1 dispersing speed from vehicle: 2.about.5 m/min PA1 number of dispersing nozzles: 10 PA1 diameter of dispersing nozzle: 2 mm
When dispersing small quantities of emulsion using conventional devices, however, the rotating speed of the emulsion pump is reduced and, if necessary, the dispersing nozzle is exchanged for one with a smaller diameter. In this case, however, if the rotating speed of the emulsion pump is reduced too much, then emulsion's discharge pressure drops, and the angle of dispersion of the emulsion from the nozzle becomes small. As a result, an interval of separation between the emulsion dispersed from adjacent dispersing nozzles occurs, so that a non-uniform application of the emulsion tends to result. Further, the smaller diameter dispersing nozzles tend to clog, again resulting in a non-uniform dispersion.